In this preclinical trial, we propose to target rho-associated protein kinase (ROCK) using fasudil in models of acute focal cerebral ischemia followed by reperfusion. ROCK is a major regulator of actin cytoskeleton controlling numerous functions in vascular smooth muscle, endothelium, neurons, glia, leukocytes and blood cells. Many of these are relevant for the pathophysiology of stroke, making ROCK a unique pleiotropic target with multiple converging and synergistic mechanisms, including cerebrovasodilation and reduced blood viscosity improving collateral flow in hyperacute stroke, and anti-inflammatory and anti-edema effects in acute to subacute stages. We and others have targeted ROCK in models of ischemic stroke in exploratory studies, vast majority of which showed improved tissue and functional outcomes, in multiple species and stroke models, and using various inhibitors and therapeutic paradigms. In a systematic review and stratified metaanalysis of 25 experimental studies, ROCK inhibition reduced infarct volume by 37% and improved neurological scores by 41%. Fasudil is the most commonly used ROCK inhibitor in experimental stroke and is off-patent to be procured in any formulation for both preclinical and clinical trials without delay. Fasudil has been the clinical standard of care for two decades in acute SAH in China and Japan, with a clean safety record. There have been numerous clinical trials of systemic fasudil in both US and abroad in healthy volunteers, and in patients with chronic cerebral infarcts, coronary artery disease, heart failure, and pulmonary hypertension among others. Indeed, in a small trial in acute stroke fasudil was efficacious. Nevertheless, none of these trials revealed any serious adverse events either with acute single doses or chronic daily dosing. We propose to confirm this promising profile in a preclinical trial using transient middle cerebral artery occlusion. Aim 1 will establish the optimal dose (Exp 1), confirm efficacy on long-term outcome (Exp 2), test whether fasudil extends the therapeutic window for recanalization (Exp 3), examine the efficacy of intraarterial delivery (Exp 4), and confirm efficacy using clinically-relevant MRI indices (Exp 5). Aim 2 will then test efficacy and safety in a clot model with or without tPA (Exp 6), and safety in comorbid hypertension and diabetes as well as combination treatments (Exp 7) and in permanent ischemia (Exp 8). The proposal comes from an experienced group of investigators with proven expertise, capable of adjusting to the needs of the network. Collectively, we have published ~100 manuscripts using various stroke models and neurocognitive and tissue readouts suitable for both acute (<72h) and chronic (up to 2 months) assessments in mice and rats. Besides the proposed experimental models, our expertise covers hemorrhagic transformation, combination treatment with tPA and ischemic brain edema. Altogether, we passionately support the concept of an unbiased multicenter preclinical testing platform such as SPAN for experimental stroke therapeutics. We are fully committed to support this network.